| 1. |
- Lopes, A. M., et al.
(författare)
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Host-Specific Glycans Are Correlated with Susceptibility to Infection by Lagoviruses, but Not with Their Virulence
- 2018
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Ingår i: Journal of Virology. - : American Society for Microbiology. - 0022-538X .- 1098-5514. ; 92:4
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Tidskriftsartikel (refereegranskat)abstract
- Rabbit hemorrhagic disease virus (RHDV) and European brown hare syndrome virus (EBHSV) are two lagoviruses from the family Caliciviridae that cause fatal diseases in two leporid genera, Oryctolagus and Lepus, respectively. In the last few years, several examples of host jumps of lagoviruses among leporids were recorded. In addition, a new pathogenic genotype of RHDV emerged, and many nonpathogenic strains of lagoviruses have been described. The molecular mechanisms behind host shifts and the emergence of virulence are unknown. Since RHDV uses glycans of the histo-blood group antigen type as attachment factors to initiate infection, we studied if glycan specificities of the new pathogenic RHDV genotype, nonpathogenic lagoviruses, and EBHSV potentially play a role in determining the host range and virulence of lagoviruses. We observed binding to A, B, or H antigens of the histo-blood group family for all strains known to primarily infect European rabbits (Oryctolagus cuniculus), which have recently been classified as GI strains. However, we could not explain the emergence of virulence, since similar glycan specificities were found in several pathogenic and nonpathogenic strains. In contrast, EBHSV, recently classified as GII. 1, bound to terminal beta -linked N-acetylglucosamine residues of O-glycans. Expression of these attachment factors in the upper respiratory and digestive tracts in three lagomorph species (Oryctolagus cuniculus, Lepus europaeus, and Sylvilagus floridanus) showed species-specific patterns regarding susceptibility to infection by these viruses, indicating that species-specific glycan expression is likely a major contributor to lagovirus host specificity and range. IMPORTANCE Lagoviruses constitute a genus of the family Caliciviridae comprising highly pathogenic viruses, RHDV and EBHSV, that infect rabbits and hares, respectively. Recently, nonpathogenic strains were discovered and new pathogenic strains have emerged. In addition, host jumps between lagomorphs have been observed. The mechanisms responsible for the emergence of pathogenicity and host species range are unknown. Previous studies showed that RHDV strains attach to glycans expressed in the upper respiratory and digestive tracts of rabbits, the likely portals of virus entry. Here, we studied the glycan-binding properties of novel pathogenic and nonpathogenic strains looking for a link between glycan binding and virulence or between glycan specificity and host range. We found that glycan binding did not correlate with virulence. However, expression of glycan motifs in the upper respiratory and digestive tracts of lagomorphs revealed species-specific patterns associated with the host ranges of the virus strains, suggesting that glycan diversity contributes to lagovirus host ranges.
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| 2. |
- Nyström, Kristina, 1977, et al.
(författare)
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Neofunctionalization of the Sec1 alpha 1,2fucosyltransferase Paralogue in Leporids Contributes to Glycan Polymorphism and Resistance to Rabbit Hemorrhagic Disease Virus
- 2015
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Ingår i: Plos Pathogens. - : Public Library of Science (PLoS). - 1553-7366 .- 1553-7374. ; 11:4
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Tidskriftsartikel (refereegranskat)abstract
- RHDV (rabbit hemorrhagic disease virus), a virulent calicivirus, causes high mortalities in European rabbit populations (Oryctolagus cuniculus). It uses alpha 1,2fucosylated glycans, histo-blood group antigens (HBGAs), as attachment factors, with their absence or low expression generating resistance to the disease. Synthesis of these glycans requires an alpha 1,2fucosyltransferase. In mammals, there are three closely located alpha 1,2fucosyltransferase genes rSec1, rFut2 and rFut1 that arose through two rounds of duplications. In most mammalian species, Sec1 has clearly become a pseudogene. Yet, in leporids, it does not suffer gross alterations, although we previously observed that rabbit Sec1 variants present either low or no activity. Still, a low activity rSec1 allele correlated with survival to an RHDV outbreak. We now confirm the association between the alpha 1,2fucosyltransferase loci and survival. In addition, we show that rabbits express homogenous rFut1 and rFut2 levels in the small intestine. Comparison of rFut1 and rFut2 activity showed that type 2 A, B and H antigens recognized by RHDV strains were mainly synthesized by rFut1, and all rFut1 variants detected in wild animals were equally active. Interestingly, rSec1 RNA levels were highly variable between individuals and high expression was associated with low binding of RHDV strains to the mucosa. Co-transfection of rFut1 and rSec1 caused a decrease in rFut1-generated RHDV binding sites, indicating that in rabbits, the catalytically inactive rSec1 protein acts as a dominant-negative of rFut1. Consistent with neofunctionalization of Sec1 in leporids, gene conversion analysis showed extensive homogenization between Sec1 and Fut2 in leporids, at variance with its limited degree in other mammals. Gene conversion additionally involving Fut1 was also observed at the C-terminus. Thus, in leporids, unlike in most other mammals where it became extinct, Sec1 evolved a new function with a dominant-negative effect on rFut1, contributing to fucosylated glycan diversity, and allowing herd protection from pathogens such as RHDV.
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| 3. |
- Azevedo, M, et al.
(författare)
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Infection by Helicobacter pylori expressing the BabA adhesin is influenced by the secretor phenotype
- 2008
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Ingår i: Journal of Pathology. - : Wiley. - 0022-3417 .- 1096-9896. ; 215:3, s. 308-316
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Tidskriftsartikel (refereegranskat)abstract
- Helicobacter pylori (Hp) infects half the world's population and causes diverse gastric lesions, from gastritis to gastric cancer. Our aim was to evaluate the significance of secretor and Lewis status in infection and in vitro adherence by Hp expressing BabA adhesin. We enrolled 304 Hp-infected individuals from Northern Portugal. Gastric biopsies, blood and saliva were collected. Polymerase chain reaction (PCR) and immunofluorescence were used to detect BabA+ Hp in gastric biopsies. In vitro adherence by a BabA expressing Hp strain to gastric biopsies was performed. Secretor status was identified by Ulex, a lectin that recognizes secretor-dependent glycan structures in saliva and in gastric mucosa, and by Lewis(a/b) antibodies, and indirectly by identification of an inactivating mutation in the FUT2 gene (G428A). BabA status of infecting Hp was associated with CagA and VacAs1 (p < 0.05), intercellular localization of Hp (p < 0.01) and the presence of intestinal metaplasia (p < 0.05) and degenerative alterations (p < 0.005) in the biopsies. BabA was associated (p < 0.05) with Ulex staining of gastric biopsies and, although not significantly, to absence of homozygosity for FUT2 G428A inactivating polymorphism. In vitro Hp adherence was higher in cases wild-type or heterozygous for FUT2 G428A mutation (p < 0.0001), cases staining for Ulex (p < 0.0001) and a(-)b+ and a(-)b(-) secretor phenotypes (p < 0.001). In conclusion, BabA+ Hp infection/adhesion is secretor-dependent and associated with the severity of gastric lesions.
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| 4. |
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| 5. |
- Gane, P, et al.
(författare)
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Heterogeneity of anti-A and anti-B monoclonal reagents. Agglutination of some weak ABH erythrocyte variants and recognition of synthetic oligosaccharide and tissue antigens.
- 1987
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Ingår i: Vox sanguinis. - 0042-9007. ; 53:2, s. 117-25
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Tidskriftsartikel (refereegranskat)abstract
- Eight anti-A and seven anti-B monoclonal reagents were tested in parallel, with normal and weak ABH red cell phenotypes. A whole range of different reactivity patterns was found, but by making a comparison with the results obtained using polyclonal standard reagents, two major categories of reagents were distinguished: (a) stronger and more specific reagents, and (b) reagents similar to, or weaker than, the standard polyclonal controls. The analysis of the specificity of the reagents by tissue fluorescence staining and reactivity with synthetic oligosaccharides and purified glycolipids confirmed the existence of broad and restricted specificities. Two kinds of anti-A1 reagents are described. One related to type 3/4 structures, which stains the Golgi apparatus, and another with broad anti-A specificity which cross-reacts with 'A-like' structures. The inhibition of anti-A reagents with salivas and synthetic oligosaccharide antigens gave parallel results for the secretor salivas and the difucosylated A antigens.
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| 6. |
- Le Pendu, J., et al.
(författare)
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Human Norovirus Receptors
- 2016
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Ingår i: Viral Gastroenteritis: Molecular Epidemiology and Pathogenesis. - : Elsevier. - 9780128026595 ; , s. 379-396
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Bokkapitel (refereegranskat)abstract
- Due to the lack of cell culture methods, studies of human norovirus receptors have been limited to virus challenge and outbreak studies and in vitro binding studies of virus-like particles (VLPs). Norovirus VLPs recognize glycans from the ABO(H) and Lewis histo-blood group family on glycoproteins and glycosphingolipids in a strain-dependent manner. Host genetic studies have shown that for the clinically dominating strains the binding pattern correlates with susceptibility to infection. Particularly, the so-called nonsecretors, characterized by their lack of expression of ABO(H) structures in the gastrointestinal tract, have been identified as resistant to infections by many strains. In support of a receptor status, norovirus VLPs have been shown to bind to intestinal epithelium expressing ABO(H) epitopes, to intestinal glycosphingolipids carrying ABO(H) epitopes and to induce membrane invaginations, resembling endocytosis intermediates, on model membranes carrying such glycosphingolipids. However, in addition to the ABO(H) structures, the VLPs also recognizes other glycans that could play an important role in virus entry into the host cells. © 2016 Elsevier Inc. All rights reserved.
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| 7. |
- Ménoret, A, et al.
(författare)
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The expression of carbohydrate blood group antigens correlates with heat resistance.
- 1995
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Ingår i: Journal of cell science. - 0021-9533. ; 108 ( Pt 4), s. 1691-701
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Tidskriftsartikel (refereegranskat)abstract
- Recent data indicate that cells may resist heat shock via more than one route: heat shock protein synthesis and other still ill-defined mechanisms. We investigated this phenomenon using four types of cells derived from a single rat colon carcinoma: clones REGb and PROb; PRO A+, a glycosylation variant of PROb selected for its high expression of blood group A antigen; and Ph8, a thermoresistant variant of PROb selected by repeated sublethal heat treatments. Basal heat resistance was clearly associated with the level of cell surface expression of blood group H and A antigens. Biosynthesis of these carbohydrate structures requires two glycosyltransferases, H and A enzymes, whose activities are also correlated with basal heat resistance. In addition, heat sensitive REGb cells were rendered more resistant by transfection with the gene encoding for H enzyme, allowing expression of H antigen. Thus, these terminal glycosylations could play a role as cellular protectors against heat treatment. Blood group carbohydrate antigens were mainly located on O-linked carbohydrate chains of a major glycoprotein of 200 kDa and to a lesser extent on N-linked chains. Only trace amounts were present as glycolipids.
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